From 5b097e79511abb83ef04401140d7dab2b42c41a3 Mon Sep 17 00:00:00 2001
From: Shenghou Ma <minux.ma@gmail.com>
Date: Sun, 2 Jun 2013 22:46:53 +0800
Subject: [PATCH] cmd/cgo: using __typeof__(a->r) instead of putting invalid
 TYPE in "a->r = (const TYPE)" Thanks kballard for the hint. Fixes #4857.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/9649045
---
 misc/cgo/test/issue4857.go | 15 +++++++++++++++
 src/cmd/cgo/out.go         |  2 +-
 2 files changed, 16 insertions(+), 1 deletion(-)
 create mode 100644 misc/cgo/test/issue4857.go

diff --git a/misc/cgo/test/issue4857.go b/misc/cgo/test/issue4857.go
new file mode 100644
index 0000000000..54dc39f8d1
--- /dev/null
+++ b/misc/cgo/test/issue4857.go
@@ -0,0 +1,15 @@
+// Copyright 2013 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package cgotest
+
+/*
+#cgo CFLAGS: -Werror
+const struct { int a; } *issue4857() { return (void *)0; }
+*/
+import "C"
+
+func test4857() {
+	_ = C.issue4857()
+}
diff --git a/src/cmd/cgo/out.go b/src/cmd/cgo/out.go
index d9f7604962..29f7020930 100644
--- a/src/cmd/cgo/out.go
+++ b/src/cmd/cgo/out.go
@@ -490,7 +490,7 @@ func (p *Package) writeOutputFunc(fgcc *os.File, n *Name) {
 	if t := n.FuncType.Result; t != nil {
 		fmt.Fprintf(fgcc, "a->r = ")
 		if c := t.C.String(); c[len(c)-1] == '*' {
-			fmt.Fprintf(fgcc, "(const %s) ", t.C)
+			fmt.Fprint(fgcc, "(__typeof__(a->r)) ")
 		}
 	}
 	fmt.Fprintf(fgcc, "%s(", n.C)
-- 
2.48.1